I decided to document my process of working through this modified version of the Gilded Rose Kata both for my own learning enjoyment as well as hopefully helping others who, like me, are trying to see more of the forest and less of the trees.
For this exercise, I began with a stripped down version of the repository with no tests in place as provided by kbaribeau here.
Stage 1 - Testing
I utilized the client specs provided below along with investigative testing to determine the effect that the update_quality method had on each item within the sample data array.
After completing the test suite for the kata's current functionality, I decided to leave both "normal" items in place for a bit just to confirm my refactorings were working as intended.
You can review my testing approach over two commits, here and here.
Stage 2 - First Refactoring
To get the refactoring rolling, I decided to give each of the special cases its own method. Rather than pick through the existing conditional reusable code, I implemented the easiest solution I could think of to get the tests back to green.
Aged Bree was very straight forward and I didn't even break the tests with Sulfuras since it doesn't really ever change.
The Backstage Passes were a little more involved. I first continued with the string of conditionals but after getting some odd test failures, I opted for a case statement just to help my mental processing. I knew I was going to be back working on the passes again in a future round of refactoring so the case statement would work fine for the time.
It was also on the Backstage Passes that I realized I had some wiggle room in my tests that would need addressing, however, I wanted to finish this round of refactoring before going off in that direction again.
You can check out my work up to this point here.here
Hi and welcome to team Gilded Rose. As you know, we are a small inn with a prime location in a prominent city run by a friendly innkeeper named Allison. We also buy and sell only the finest goods. Unfortunately, our goods are constantly degrading in quality as they approach their sell by date. We have a system in place that updates our inventory for us. It was developed by a no-nonsense type named Leeroy, who has moved on to new adventures. Your task is to add the new feature to our system so that we can begin selling a new category of items. First an introduction to our system:
- All items have a SellIn value which denotes the number of days we have to sell the item
- All items have a Quality value which denotes how valuable the item is
- At the end of each day our system lowers both values for every item
Pretty simple, right? Well this is where it gets interesting:
- Once the sell by date has passed, Quality degrades twice as fast
- The Quality of an item is never negative
- "Aged Brie" actually increases in Quality the older it gets
- The Quality of an item is never more than 50
- "Sulfuras", being a legendary item, never has to be sold or decreases in Quality
- "Backstage passes", like aged brie, increases in Quality as it's SellIn value approaches; Quality increases by 2 when there are 10 days or less and by 3 when there are 5 days or less but Quality drops to 0 after the concert
We have recently signed a supplier of conjured items. This requires an update to our system:
- "Conjured" items degrade in Quality twice as fast as normal items
Feel free to make any changes to the UpdateQuality method and add any new code as long as everything still works correctly. However, do not alter the Item class or Items property as those belong to the goblin in the corner who will insta-rage and one-shot you as he doesn't believe in shared code ownership (you can make the UpdateQuality method and Items property static if you like, we'll cover for you). Your work needs to be completed by Friday, February 18, 2011 08:00:00 AM PST.
Just for clarification, an item can never have its Quality increase above 50, however "Sulfuras" is a legendary item and as such its Quality is 80 and it never alters.